Fluorescent gaseous discharge lamp system and thermal starting switch



J. KURTZ ET AL June 24, 1947.

FLUORESCENT GASEOUS DISCHARGE LAMP-SYSTEM AND THERMAL STARTING SWITCH Filed June 4, 1942 ATTORNEY Patented June 24, 1947 FLUORESCENT GASEOUS DISCHARGE LAMP SYSTEM AND THERMAL START- ING SWITCH Jacob Kurtz, Teaneck, N. J James Waldie, New York, N. Y., and Joseph Spina, Cliffside Park, N. J., assignors to Callite Tungsten Corporation, Union City, N. J., a corporation of Delaware Application June 4, 1942, Serial No. 445,734

5 Claims. 1 This invention relates to electric gaseous discharge lamps and in particular to circuits for fluorescent discharge tubes starting at high voltages and operating with constant current transformers of the usual type.

One of the objects of this invention is to provide 5 which the contacts 5 are mounted, causing their a novel, simple and efficient circuit arrangement opening, This opens the short circuit around whereby electric gase s arge tubes can 01 lamp 3 and eiiectively includes it in the secondary erate eflici ently, and where the secondary current circuit in series with lamp W111 remaln relatively Constant in p t of e it) A condenser I provided in series with the lamp normal P y Voltage Variations encountered i 2 improves the power factor and helps in starting servlcethe second lamp 3, and the bridging condenser 8 A further obJect is to obtain instantaneous prevents parking at the contacts t g n o more lamps in a group. a p The following is a tabulation of the significant crating in series, where no auxiliary transformers data and resuus Obtained; or inductance coils are required.

Still another object is to provide a simple COndenSeI Infd' balanced circuit using a constant current trans- Condenser former adaptable to a wide variety of lamps, Tubes 2 d 3! Other objects, features and advantages will be- Diamete1-25 come apparent from the following detailed de- Length-4} scription of various embodiments of the inven- GasArgO at /2 tion as applied the schematic diagrams of which Starting V01tage-350400 Volts Fig. 1 illustrates a two-tube circuit provided Op a V l Vo ts R- M- S. at with a starting switch; 350 ma. tube current.

Fig. 2 a four-tube circuit with dual starting Light D 130 foot Candle p foot switches; (fa/ft.) at 350 wa. at 24 hours life.

Circuit data Line Line Tube g in gggg t vttt s 233? 53 Fc/fi- 31522315 tfiit Fig. 2a a modification of Fig. 2; and Pressure is an important factor. In the above Fig. 3 is a perspective of the dual control example, best over-all results were obtained at thermostatic switch used in Fig. 2. 40 the higher values.

Referring to the circuit shown in Fig. l, the In prior system in W i h gaseous dischar e customary neon sign tube, constant current tubes were operated over constant current voltage transformer I of the high leakage, high reactance transformers only a maximum of four feet of type (120 volts primary, 560 volts secondary, 360 25 mm. tubing could be connected because longer ma. secondary short-circuit), or the equivalent, tubes caused the secondary current to drop below is used to connect fluorescent tubes 2 and 3 with the best operating value of 300 ma. Furtherthe power mains. more, in such arrangements the power factor was When the main switch in the primary is closed, only about .34 and only 27 lumens per watt were the full voltage of the current in the secondary produced. circuit is across lamp 2, lamp 3 being effectively 50 Fig. 2 shows a circuit diagram expanded to illusshort circuited in normally closed contacts 4 of a trate how this method of operation can be utilized thermostatic switch 5. A very short time after to get dual operation from a single transformer the primary circuit is closed, the self-heating having a center tapped secondary, shown in Fig. cathodes of lamp 2 of the type described in my 2a, or two like transformers having substantially Patent 2,244,070 become efficient electron emit- 5 the same characteristics. In this case the therters and the voltage across the lamp drops down to a value of approximately volts, for the 4 ft. tube, and 225 volts for the 6 it. tube.

The current flows through contacts 4 and heating coil 6 which heats the bimetallic blades on mostatic switch has a dual control for each circuit and has a common lead to the midpoint of its heating coil. One half of the coil controls one circuit and the other half the second circuit.

Four tubes l0, ll, l2 and l3 are fed either by a single transformer l4 having a center tapped secondary or by two like transformers having the same characteristics.

The double thermostatic switch 55 has two sets of normally closed contacts ltd, lfib and ill) and a common heating coil I8. is shown in Fig. 3, the switch is mounted on a base 23 of insulating material. From this base project three stems 24 on which the resistance [8 is mounted, the stems being connected with plugs like 25 projecting from the base to the outside and through which connections may be established with the circuit. The lower half of heating coil 18 is straddled by the bimetallic switching con tacts Ila, Nb and contacts lfia, [6b straddle the upper half of the coil. Contacts Ila Ida are welded to two of the stems 24 and contacts l'ib to stems 26, the latter connected with plugs 27. The switch may be enclosed by a cover it: seated on the base 2 Contacts lfia and it?) are bridged by condenser 28, and contacts lid and lib by condenser 29. The base 23 is of the fivepin octal type having a keyed. guide pin so arranged as to make sure that the switch will be correctly seated in its socket and connected with the circuit. When the main switch in the transformer primary circuit is closed, lamps isand i3 will be started over the following circuits: Transformer secondary 20, lamp H1, contacts lea, upper half of coil l8, and condenser l9, secondary 22, lamp !3, contacts lla, llb, lower half of coil 58, and condenser 2!. As in Fig. 1, when the lamps start, the heating coil !8 will open the contacts Eta, E61) and lid, Ilb which will open the normal short circuit around lamps l l and i2 and connect these in series with H] and 3.

The values are the same as in Fig. 1. The two circuits are about 180 out of phase. The power factor is better than 90%.

The transformer l4 and the condensers l5 and 2! are enclosed in a shielded casing.

What we claim is:

1. In combination, a transformer having a pri mary and secondary windings, four gaseous discharge lamps, a thermostatic switch having a heating coil, divided into two halves, and two pairs of bimetallic contacts controlled by the two halves of the heating coil, respectively, a circuit including in series the secondary winding, two lamps, a condenser, and one half of the heating coil, a short circuit across one of the last Inentioned two lamps over the bimetallic contacts adjacent said one half of the heating coil, a second circuit including in series th second secondary winding, the two other lamps, a condense and the other half of the heating coil, and a short-circuit across one of the two last mentioned lamps over the bimetallic contacts controlled by the last mentioned half of the heating coil.

2. In combination, a constant current transformer having a divided primary and divided secondary winding, four fluorescent tubes each having two electrodes, a thermostatic switch having a. heating coil and two pairs of bimetallic contacts controlled by the two halves of the heating coil, respectively, a circuit including in series one of the secondar; windings, two of said tubes, one half of the heating coil and a condenser, a short-circuit across one of the last mentioned two tubes over the bimetallic contacts adjacent said one half of the heating coil, a condenser bridging the last mentioned contacts, a second circuit including in series the other secondary winding, the two other tubes, the other half of the heating coil, and a condenser, a short-circuit across one of the two last mentioned tubes over the bimetallic contacts controlled by the last mentioned half of the heating coil, and a condenser bridging the last mentioned bimetallic contacts.

3. In a thermostatic switch, a base, connecting pins projecting from one side thereof, conductors connected with said pins projecting from the other side thereof, two bimetallic strips arranged to face one another with a space between them, and having one of their ends connected with and mounted on two of said conductors, the other ends of said strips having contacts and being free to move towards and away from one another, and heating coil arranged in said space and connected to one of the last mentioned conductors .d another conductor, one sector of the circumence of said cell bein arranged to heat one i said strips and an opposite sector of said coil voeing arranged to heat the other of said strips,

l. In a thermostatic switch, the combination base, connecting pins projecting from one 7 thereof, conductors connected with said pins ecting from the other side thereof, a plurality irs of bi i etallic strips, the strips of each pair arranged to face one another with a space between them, and having one of their ends connected with mounted on said conductors, the

" r ends of said strips having contacts and free to move towards and away from one another, and a heating coil passing through the space between the individual strips of each pair and connected to certain of said conductors, one sector of the circumference of said coil being arranged to heat one strip of each pair on one Lde of said coil and an opposite sector of said coil bein arranged to heat the strips of each pair ai anged on the opposite side of said coil.

5. In a thermostatic switch, a base, five connecting pins projecting from one side thereof, five conductors connected with said pins projecting from the other side thereof, two pairs of bimetallic strips, th strips of each pair being arranged to face one another with a space between them, each strip having one end connected with and moun ed on a different conductor, the other end of each strip having contacts and being free to move towards and away from the corresponding end of its pair, a heating coil passing through the space between the individual strips of each pair so that each half of said coil is arranged between the individual strips of one pair, whereby one sector of the circumference of each coil half is arranged to heat one strip of one pair and an opposite sector of said coil half is arranged to heat the other strip of said pair, and a cover for said case enclosing said contacts, conductors and coil.

JACOB KURTZ. JAMES WALDIE. JOSEPH SPINA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number (Other references on following page) Number UNITED STATES PATENTS Name Date Peters Apr. 1, 1941 Lord Aug. 25, 1942 Peters Aug. 25, 1942 Spanner Sept. 29, 1942 Prescott Nov. 3, 1942 McCarthy Dec. 30, 1941 Number Campbell Dec, 16, 1941 Abbott Dec. 30, 1941 Bechter Sept. 12, 1939 FOREIGN PATENTS Country Date Great Britain Mar. 3, 1932 Great Britain Nov. 7, 1934 Great Britain Apr. 27, 1933 

